java - localhost api 请求的 Http 失败响应 : 0 Unknown Error - Angular

Question

我正在尝试从 Angular 应用程序创建与 Java Jetty 后端的通信。当我尝试执行我的请求时，我收到以下错误:

我在客户端的代码:(Angular 7.2.1)。我还使用 HttpInterceptor 进行身份验证，应该可以工作。我还在开发模式下使用 ngserve 运行代码。

@Injectable({
    providedIn: 'root'
})
export class NgHydrantService {

    constructor(private http: HttpClient) {
    }
  
    public register(entity: IEntityDescription): Observable<StandardResponsePacket> {
        let packet = new RegisterEntityRequestPacket(entity);
        return this.http.post(this._apiUrl, packet.toJson())
            .pipe(
                map(value => {
                    console.log('register result:', value); //<-- never executed
                    return <StandardResponsePacket>HydrantPackage.fromJson(value)
                })
            );

    }
}

//The interceptor
intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        // add authorization header with basic auth credentials if available
        if (this.user != null) {

            const clonedRequest = request.clone({
                headers: request.headers.set('Authorization', `Basic ${this.user.getAuth()}`)
                                        .set('Accept','application/json')
            });
            //This debug line works and looks good!
            console.log('NgHydrantAuthInterceptor#intercept', clonedRequest);
            return next.handle(clonedRequest);
        }

        return next.handle(request);
    }

我在服务器端的代码:(Jetty-9.4.14.v20181114)在本地主机上运行。

public final class PacketHandler extends AbstractHandler
{
  @Override
  public void handle( String target,
                    Request baseRequest,
                    HttpServletRequest request,
                    HttpServletResponse response ) throws IOException
  {
    try
    {
        // Declare response encoding and types
        response.setContentType( "application/json; charset=utf-8" );
        // Enable CORS
        response.addHeader("Access-Control-Allow-Origin", "*");
        response.addHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE, HEAD");
        response.addHeader("Access-Control-Allow-Headers", "X-PINGOTHER, Origin, X-Requested-With, Content-Type, Accept");
        response.addHeader("Access-Control-Max-Age", "1728000");
        //... more stuff
    }
    finally
    {
        // Inform jetty that this request was handled
        baseRequest.setHandled( true );
    }
  }
}

我检查的事情:

• 在研究过程中，有些人提到了 CORS 的问题(这就是我在服务器端代码中添加 header 条目的原因)
• 在 Postman 中执行相同的请求没有任何问题
• 服务器端没有日志

我的问题是关于在开发过程中从服务器获取响应的可能解决方案。

Answer 1

您可以按照以下链接中的步骤操作吗 https://www.html5rocks.com/en/tutorials/cors/要快速解决方案，请在 chrome 中添加以下插件 https://chrome.google.com/webstore/detail/allow-control-allow-origi/nlfbmbojpeacfghkpbjhddihlkkiljbi?hl=en